Switching between packet duplication operating modes

ABSTRACT

For switching between packet duplication operating modes, methods, apparatus, and systems are disclosed. One apparatus includes a processor and a transceiver that communicates with a mobile communication network via a radio bearer. The processor determines whether PDCP packet duplication associated with the PDCP protocol entity is to be activated and, if so, communicates with a mobile communication network according to a packet duplication mode of operation. Otherwise, the processor determines whether a split threshold value of the PDCP protocol entity is set to a predefined value, communicates with the mobile communication network according to a first split bearer mode of operation in response to determining that the split threshold value is set to the predefined value, and communicates with the mobile communication network according to a second split bearer mode of operation in response to determining that the split threshold value is not set to the predefined value.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is continuation of and claims priority to claimspriority to U.S. patent application Ser. No. 16/877,157 entitled“Switching Between Packet Duplication Operating Modes” and filed on May18, 2020 for Joachim Lohr, Prateek Basu Mallick, and Ravi Kuchibhotla;to U.S. patent application Ser. No. 16/557,038 entitled “SwitchingBetween Packet Duplication Operating Modes” and filed on Aug. 30, 2019for Joachim Lohr, Prateek Basu Mallick, and Ravi Kuchibhotla; and U.S.patent application Ser. No. 15/953,248 entitled “Switching BetweenPacket Duplication Operating Modes” and filed on Apr. 13, 2018 forJoachim Lohr, Prateek Basu Mallick, and Ravi Kuchibhotla; and U.S.Provisional Application No. 62/542,284 entitled “Selective PacketDuplication Control” and filed Aug. 7, 2017; and U.S. ProvisionalApplication No. 62/489,332 entitled “Efficient Scheme for PacketDuplication in NR” and filed Apr. 24, 2017, the entire disclosures ofeach are hereby incorporated by reference.

FIELD

The subject matter disclosed herein relates to electronic communicationsand more particularly relates to switching between packet duplicationoperating modes.

BACKGROUND

The following abbreviations and acronyms are herewith defined, at leastsome of which are referred to within the following description.

Third Generation Partnership Project (“3GPP”), Access and MobilityManagement Function (“AMF”), Access Point Name (“APN”), Access Stratum(“AS”), Backoff Indicator (“BI”), Bandwidth Part (“BWP”), CarrierAggregation (“CA”), Clear Channel Assessment (“CCA”), Control ChannelElement (“CCE”), Channel State Information (“C SI”), Common Search Space(“CSS”), Data Network Name (“DNN”), Data Radio Bearer (“DRB”), DownlinkControl Information (“DCI”), Downlink (“DL”), Enhanced Clear ChannelAssessment (“eCCA”), Enhanced Mobile Broadband (“eMBB”), Evolved Node-B(“eNB”), Evolved Packet Core (“EPC”), Evolved UMTS Terrestrial RadioAccess Network (“E-UTRAN”), European Telecommunications StandardsInstitute (“ETSI”), Frame Based Equipment (“FBE”), Frequency DivisionDuplex (“FDD”), Frequency Division Multiple Access (“FDMA”), GloballyUnique Temporary UE Identity (“GUTI”), Hybrid Automatic Repeat Request(“HARQ”), Home Subscriber Server (“HSS”), Internet-of-Things (“IoT”),Key Performance Indicators (“KPI”), Licensed Assisted Access (“LAA”),Load Based Equipment (“LBE”), Listen-Before-Talk (“LBT”), Long TermEvolution (“LTE”), LTE Advanced (“LTE-A”), Medium Access Control(“MAC”), Multiple Access (“MA”), Modulation Coding Scheme (“MCS”),Machine Type Communication (“MTC”), Massive MTC (“mMTC”), MobilityManagement (“MM”), Mobility Management Entity (“MME”), Multiple InputMultiple Output (“MIMO”), Multipath TCP (“MPTCP”), Multi User SharedAccess (“MUSA”), Non-Access Stratum (“NAS”), Narrowband (“NB”), NetworkFunction (“NF”), Next Generation (e.g., 5G) Node-B (“gNB”), NextGeneration Radio Access Network (“NG-RAN”), New Radio (“NR”), PolicyControl & Charging (“PCC”), Policy Control Function (“PCF”), PolicyControl and Charging Rules Function (“PCRF”), Packet Data ConvergenceProtocol (“PCDP”), Packet Data Network (“PDN”), Packet Data Unit(“PDU”), PDN Gateway (“PGW”), Quality of Service (“QoS”), QuadraturePhase Shift Keying (“QPSK”), Radio Access Network (“RAN”), Radio AccessTechnology (“RAT”), Radio Resource Control (“RRC”), Receive (“RX”),Switching/Splitting Function (“S SF”), Scheduling Request (“SR”),Serving Gateway (“SGW”), Session Management Function (“SMF”), SystemInformation (“SI”), System Information Block (“SIB”), Transport Block(“TB”), Transport Block Size (“TB S”), Time-Division Duplex (“TDD”),Time Division Multiplex (“TDM”), Transmission and Reception Point(“TRP”), Transmit (“TX”), Uplink Control Information (“UCI”), UnifiedData Management (“UDM”), User Entity/Equipment (Mobile Terminal) (“UE”),Uplink (“UL”), User Plane (“UP”), Universal Mobile TelecommunicationsSystem (“UMTS”), Ultra-reliability and Low-latency Communications(“URLLC”), and Worldwide Interoperability for Microwave Access(“WiMAX”).

Packet duplication adds redundant information to transmissions betweendevices to accommodate for errors during the transmissions. Bytransmitting duplicate data within the transmission, a transmittingdevice increases the probability that the corresponding receiving devicewill successfully receive the data in its entirety. In environments withlow transmission reliability, the duplicate data improves the overalldata error rate, since it is unlikely the transmissions will corrupt thesame set of data in both a first and second instance of the duplicatedata. In other words, a receiving device can combine the uncorrupteddata from each instance of the duplicate data to successfully receiveand extract data. However, in environments with high transmissionreliably, the addition of duplicate data can occupy valuable data spaceand/or add unnecessary overhead to transmissions that are operatingwithout error. Conversely, if the environments with high transmissionreliability omit transmitting the duplicate data, it becomes harder fordevices operating in the high transmission reliability environment torecover from temporary failures or unanticipated changes.

BRIEF SUMMARY

Methods for switching between packet duplication operating modes aredisclosed. Apparatuses and systems also perform the functions of themethods. One method (e.g., of a user equipment) for switching betweenpacket duplication operating modes includes establishing a radio bearerto communicate with at least one network entity, the radio bearercomprising a Packet Data Convergence Protocol (“PDCP”) protocol entityassociated with a first Radio Link Control (“RLC”) protocol entity andwith a second RLC protocol entity. The method includes determiningwhether PDCP packet duplication associated with the PDCP protocol entityis to be activated and communicating with a mobile communication networkaccording to a packet duplication mode of operation in response todetermining that PDCP packet duplication is to be activated. The methodincludes determining whether a split threshold value of the PDCPprotocol entity is set to a predefined value in response to determiningthat PDCP packet duplication is not to be activated, communicating withthe mobile communication network according to a first split bearer modeof operation in response to determining that the split threshold valueis set to the predefined value, and communicating with the mobilecommunication network according to a second split bearer mode ofoperation in response to determining that the split threshold value isnot set to the predefined value.

In various embodiments, the first split bearer mode of operationincludes selecting one of the first RLC protocol entity and the secondRLC protocol entity to be a primary RLC protocol entity and transmittinguplink PDCP data exclusively over a data path associated with theprimary RLC protocol entity. In various embodiments, the second splitbearer mode of operation comprises includes selecting one of the firstRLC protocol entity and the second RLC protocol entity to be a primaryRLC protocol entity and selectively sending uplink PDCP data to theprimary RLC protocol entity or to a non-primary RLC protocol entitybased on an amount of uplink PDCP data as compared to the splitthreshold value.

BRIEF DESCRIPTION OF THE DRAWINGS

A more particular description of the embodiments briefly described abovewill be rendered by reference to specific embodiments that areillustrated in the appended drawings. Understanding that these drawingsdepict only some embodiments and are not therefore to be considered tobe limiting of scope, the embodiments will be described and explainedwith additional specificity and detail through the use of theaccompanying drawings, in which:

FIG. 1 illustrates an example operating environment in accordance withone or more implementations;

FIG. 2 is a bounce diagram that illustrates various interactions betweenentities in accordance with one or more implementations;

FIG. 3 is an example flow diagram that illustrates operations ofselectively controlling packet duplication at user equipment inaccordance with one or more implementations;

FIG. 4 is an example flow diagram that illustrates operations ofselectively switching between modes of operation in accordance with oneor more implementations;

FIG. 5 illustrates various components of an example device that canimplement various implementations; and

FIG. 6 illustrates various components of an example device that canimplement various implementations.

DETAILED DESCRIPTION

As will be appreciated by one skilled in the art, aspects of theembodiments may be embodied as a system, apparatus, method, or programproduct. Accordingly, embodiments may take the form of an entirelyhardware embodiment, an entirely software embodiment (includingfirmware, resident software, micro-code, etc.) or an embodimentcombining software and hardware aspects.

For example, the disclosed embodiments may be implemented as a hardwarecircuit comprising custom very-large-scale integration (“VLSI”) circuitsor gate arrays, off-the-shelf semiconductors such as logic chips,transistors, or other discrete components. The disclosed embodiments mayalso be implemented in programmable hardware devices such as fieldprogrammable gate arrays, programmable array logic, programmable logicdevices, or the like. As another example, the disclosed embodiments mayinclude one or more physical or logical blocks of executable code whichmay, for instance, be organized as an object, procedure, or function.

Furthermore, embodiments may take the form of a program product embodiedin one or more computer readable storage devices storing machinereadable code, computer readable code, and/or program code, referredhereafter as code. The storage devices may be tangible, non-transitory,and/or non-transmission. The storage devices may not embody signals. Ina certain embodiment, the storage devices only employ signals foraccessing code.

Any combination of one or more computer readable medium may be utilized.The computer readable medium may be a computer readable storage medium.The computer readable storage medium may be a storage device storing thecode. The storage device may be, for example, but not limited to, anelectronic, magnetic, optical, electromagnetic, infrared, holographic,micromechanical, or semiconductor system, apparatus, or device, or anysuitable combination of the foregoing.

More specific examples (a non-exhaustive list) of the storage devicewould include the following: an electrical connection having one or morewires, a portable computer diskette, a hard disk, a random-access memory(“RAM”), a read-only memory (“ROM”), an erasable programmable read-onlymemory (“EPROM” or Flash memory), a portable compact disc read-onlymemory (“CD-ROM”), an optical storage device, a magnetic storage device,or any suitable combination of the foregoing. In the context of thisdocument, a computer readable storage medium may be any tangible mediumthat can contain, or store a program for use by or in connection with aninstruction execution system, apparatus, or device.

Reference throughout this specification to “one embodiment,” “anembodiment,” or similar language means that a particular feature,structure, or characteristic described in connection with the embodimentis included in at least one embodiment. Thus, appearances of the phrases“in one embodiment,” “in an embodiment,” and similar language throughoutthis specification may, but do not necessarily, all refer to the sameembodiment, but mean “one or more but not all embodiments” unlessexpressly specified otherwise. The terms “including,” “comprising,”“having,” and variations thereof mean “including but not limited to,”unless expressly specified otherwise. An enumerated listing of itemsdoes not imply that any or all of the items are mutually exclusive,unless expressly specified otherwise. The terms “a,” “an,” and “the”also refer to “one or more” unless expressly specified otherwise.

As used herein, a list with a conjunction of “and/or” includes anysingle item in the list or a combination of items in the list. Forexample, a list of A, B and/or C includes only A, only B, only C, acombination of A and B, a combination of B and C, a combination of A andC or a combination of A, B and C. As used herein, a list using theterminology “one or more of” includes any single item in the list or acombination of items in the list. For example, one or more of A, B and Cincludes only A, only B, only C, a combination of A and B, a combinationof B and C, a combination of A and C or a combination of A, B and C. Asused herein, a list using the terminology “one of” includes one and onlyone of any single item in the list. For example, “one of A, B and C”includes only A, only B or only C and excludes combinations of A, B andC. As used herein, “a member selected from the group consisting of A, B,and C,” includes one and only one of A, B, or C, and excludescombinations of A, B, and C.” As used herein, “a member selected fromthe group consisting of A, B, and C and combinations thereof” includesonly A, only B, only C, a combination of A and B, a combination of B andC, a combination of A and C or a combination of A, B and C.

Furthermore, the described features, structures, or characteristics ofthe embodiments may be combined in any suitable manner. In the followingdescription, numerous specific details are provided, such as examples ofprogramming, software modules, user selections, network transactions,database queries, database structures, hardware modules, hardwarecircuits, hardware chips, etc., to provide a thorough understanding ofembodiments. One skilled in the relevant art will recognize, however,that embodiments may be practiced without one or more of the specificdetails, or with other methods, components, materials, and so forth. Inother instances, well-known structures, materials, or operations are notshown or described in detail to avoid obscuring aspects of anembodiment.

Aspects of the embodiments are described below with reference toschematic flowchart diagrams and/or schematic block diagrams of methods,apparatuses, systems, and program products according to embodiments. Itwill be understood that each block of the schematic flowchart diagramsand/or schematic block diagrams, and combinations of blocks in theschematic flowchart diagrams and/or schematic block diagrams, can beimplemented by code. This code may be provided to a processor of ageneral-purpose computer, special purpose computer, or otherprogrammable data processing apparatus to produce a machine, such thatthe instructions, which execute via the processor of the computer orother programmable data processing apparatus, create means forimplementing the functions/acts specified in the schematic flowchartdiagrams and/or schematic block diagrams.

The code may also be stored in a storage device that can direct acomputer, other programmable data processing apparatus, or other devicesto function in a particular manner, such that the instructions stored inthe storage device produce an article of manufacture includinginstructions which implement the function/act specified in the schematicflowchart diagrams and/or schematic block diagrams.

The code may also be loaded onto a computer, other programmable dataprocessing apparatus, or other devices to cause a series of operationalsteps to be performed on the computer, other programmable apparatus, orother devices to produce a computer implemented process such that thecode which execute on the computer or other programmable apparatusprovide processes for implementing the functions/acts specified in theschematic flowchart diagrams and/or schematic block diagram.

The schematic flowchart diagrams and/or schematic block diagrams in theFigures illustrate the architecture, functionality, and operation ofpossible implementations of apparatuses, systems, methods, and programproducts according to various embodiments. In this regard, each block inthe schematic flowchart diagrams and/or schematic block diagrams mayrepresent a module, segment, or portion of code, which includes one ormore executable instructions of the code for implementing the specifiedlogical function(s).

It should also be noted that, in some alternative implementations, thefunctions noted in the block may occur out of the order noted in theFigures. For example, two blocks shown in succession may, in fact, beexecuted substantially concurrently, or the blocks may sometimes beexecuted in the reverse order, depending upon the functionalityinvolved. Other steps and methods may be conceived that are equivalentin function, logic, or effect to one or more blocks, or portionsthereof, of the illustrated Figures.

The description of elements in each figure may refer to elements ofproceeding figures. Like numbers refer to like elements in all figures,including alternate embodiments of like elements.

Overview

Various implementations selectively enable and disable packetduplication in a wireless network, such as a wireless network thatemploys Packet Data Convergence Protocol (PDCP). While features andconcepts for selectively enabling and disabling packet duplication canbe implemented in any number of different devices, systems,environments, and/or configurations, example implementations aredescribed in the context of the following example devices, systems, andmethods.

Example Operating Environment

FIG. 1 illustrates example environment 100 according to one or moreimplementations. Environment 100 includes user equipment (UE) 102illustrated as a cellular phone. In environment 100, user equipment 102includes the capability of communicating over a wireless network,generally indicated here as communication cloud 104. To represent thevarious components that make up a wireless network, environment 100generally includes network component 106-1, network component 106-2, andnetwork component 106-n, where n is an arbitrary number that indicates awireless network can include any suitable number of components. Here,each network component is illustrated as a base station that works inconjunction with other network components to provide serving cells(associated with communication cloud 104) to various types of userequipment and/or user devices. Some implementations of user equipment102 can support simultaneous connections to multiple network componentsas further described herein.

Communication cloud 104 generally represents any suitable type ofwireless network that facilitates a bi-directional link between userequipment, such as user equipment 102, and various network components(e.g., at least one of network component 106-1, network component 106-2,and network component 106-n). Communication cloud 104 can includemultiple interconnected communications networks that comprise aplurality of interconnected elements, and support any suitable type ofwireless network and/or communication system. For instance, in someimplementations, communication cloud 104, as supported by the variousnetwork components, includes the ability to support Long-Term Evolution(LTE) communications, such as those described with respect to 3^(rd)Generation Partnership Project (3GPP) and 4^(th) Generation (4G) LTE,5^(th) Generation (5G) technologies, and so forth.

In environment 100, user equipment 102 includes a UE protocol module108. Here, UE protocol module 108 represents functionality that providesthe ability to communicate via communication cloud 104 and/or itsvarious network components using a corresponding wireless networkingtechnology. For example, in the example in which communication cloud 104supports communications as described by the various LTE communicationstandards, UE protocol module 108 includes a corresponding LTE protocolstack. For simplicity's sake, UE protocol module 108 is illustrated as asingle module, but it is to be appreciated that various combinations ofsoftware, firmware, and/or hardware can be used to implement UE protocolmodule 108. As one example, UE protocol module 108 can include variouscombinations of software, firmware, control logic, and/or hardware toimplement a protocol stack based upon the Open Systems Interconnection(OSI) model that includes multiple layers (e.g., a physical layer, adata link layer, a network layer, etc.). Some implementationsadditionally partition these various layers. As one example, the datalink layer can include a Media Access Control layer (MAC) that controlsthe various permissions used to govern how user equipment 102 transmitsdata. As another example, the physical layer of UE protocol module 108can include hardware used to transmit various electrical signals and/orlow-level software access used to configure the hardware. These variouslayers are then used to communicate data to other protocol stacks asfurther described herein.

UE protocol module 108 includes UE duplication control module 110. Whileillustrated as residing within UE protocol module 108, otherimplementations of UE duplication control module 110 reside outside ofUE protocol module 108 such that UE duplication control module 110controls various aspects of UE protocol module, such as those pertainingto packet duplication. UE duplication control module 110 representsfunctionality that dynamically and/or selectively enables and disablespacket duplication as further described herein. For instance, UEduplication control module 110 can initially set various parameters usedby UE protocol module 108 to default values that enable packetduplication. Alternately or additionally, UE duplication control modulecan receive indications from external entities, such as one of networkcomponent 106-1, network component 106-2, and/or network component106-n, to disable packet duplication as further described herein. Whileillustrated as a single entity included in UE protocol module 108, it isto be appreciated that UE duplication control module 110 can beimplemented in varying combinations of software, firmware, controllogic, and/or hardware. Alternately or additionally, UE duplicationcontrol module 110 can reside in either a single layer of acorresponding protocol stack of UE protocol module 108, or in multiplelayers of the corresponding protocol stack.

In environment 100, network component 106-n includes network entity (NE)112. Here, network entity 112 represents functionality used to managecommunications over communication cloud 104. Thus, in environment 100,network entity 112 can monitor and manage various aspects of how userequipment 102 transmits data over communication cloud 104. To manage andsupport the various types of devices communicating over communicationcloud 104, network entity 112 includes NE protocol module 114 toimplement functionality corresponding to a protocol stack. For instance,returning to the example of communication cloud 104 supporting variousforms of LTE wireless communications, NE protocol module 114 can includean LTE protocol stack corresponding to a network side device that iscomplimentary to a protocol stack included in UE protocol module 108corresponding to user equipment. As one skilled in the art willappreciate, this can include the ability for various layers between thetwo protocol modules to communicate with one another (e.g., the physicallayer corresponding to UE protocol module 108 communicating with thephysical layer corresponding to NE protocol module 114, etc.). To managepacket duplication over communication cloud 104, NE protocol module 114includes NE duplication control module 116.

NE duplication control module 116 represents functionality that canmonitor and or manage selective duplication of packets at a userequipment as further described herein. In some implementations, NEduplication control module 116 initiates and/or transmits indications touser equipment 102 (that are subsequently processed by UE duplicationcontrol module 110) to selectively enable or disable packet duplication.While illustrated as a single entity included in NE protocol module 114,it is to be appreciated that NE duplication control module 116 canalternately be implemented external to NE protocol module 114. Further,NE protocol module 114 can be implemented in varying combinations ofsoftware, firmware, control logic, and/or hardware. As in the case of UEduplication control module 110, NE duplication control module 116 canreside in either a single layer of a corresponding protocol stack of NEprotocol module 114, or in multiple layers of the corresponding protocolstack.

Having described an example operating environment that can employselective packet duplication using PDCP, consider now a discussion ofdynamically selecting packet duplication in accordance with one or moreimplementation.

Dynamic Selection of Packet Duplication

Various aspects of various implementations provide dynamic selection ofpacket duplication. In some aspects, Packet Data Convergent Protocol(PDCP) protocol for New Radio (NR) supports packet duplication for bothU-Plane as well as C-Plane data of a protocol stack in order to increasethe reliability of transmissions, i.e. by having the diversity gainduring transmissions through different paths. Duplication is a functionof the PDCP layer where data, e.g., PDCP Protocol Data Units (PDUs), isduplicated. Services which benefit from duplication are Ultra-Reliableand Low-Latency Communications (URLLC) or Signalling Radio bearers(SRB)s. Transmission reliability and latency enhancements are two keyaspects for URLLC (Ultra-Reliable and Low-Latency Communications)services. Redundancy/diversity schemes in Carrier aggregation (CA)scenarios can be used to reach the reliability and latency requirementsof URLLC. For URLLC, two independent transmission channels on differentcarriers might be needed for extreme-reliability cases such as errorrates of 10⁻⁵ to 10⁻⁹ within a given latency bound. Duplication based onCA can be seen as a complementary tool for the scheduler to furtherimprove the transmission reliability. It becomes especially interestingin scenarios where reliability on one of the carriers cannot beguaranteed. In these scenarios it is thus beneficial to have furthercarrier(s) available, for example in situations like a temporaryoutage/fading dip, or due to unanticipated change or wrong channel stateinformation.

In some aspects, packet duplication can be applied based on DualConnectivity (DC) architecture, i.e. split bearer operation with PDCPduplication. In a general sense packet duplication can be used togetherwith different diversity schemes involving more than one radio link toserve a UE, e.g. dual-connectivity (DC) and carrier aggregation (CA)based architecture.

In order to reduce the overhead of duplicated transmissions it can bebeneficial to activate/deactivate PDCP duplication in a more dynamicmanner. Essentially duplication should be limited to those situationswhere the extra reliability is really needed. PDCP control signaling orMAC control signaling (MAC CE) could be for example used toactivate/deactivate PDCP duplication. However, it is not clear, how theprocedures for configuring PDCP duplication in a CA as well as DC-basedarchitecture look like and how activating/deactivating duplication in aflexible, dynamic manner is done.

Aspects of various implementations provide efficientactivation/deactivation of PDCP duplication for both CA and DC-basedarchitectures. As an example, various implementations provide supportfor the following new procedures:

-   -   1. DC and CA modes of operation: Support of split bearer with        duplication mode and use of MAC CE to turn on and off        duplication. Handling of RLC entity and buffer stats reporting        for duplication mode. Identification of RLC entity to use for        when the split bearer operates in non-duplication mode        respectively in response to duplication being turned off.        Setting of parameters such as ul-DataSplitThreshold. Split        bearer can operate in multiple modes: split bearer for        throughput improvement, split bearer with single link active or        split bearer with duplication mode activated.    -   2. A new duplication bearer type is proposed for support of        duplication. This bearer type uses MAC CE to turn on and off        duplication. In case duplication is deactivated one of the legs        is not active or suspended.    -   3. For both above modes of operation new behavior for PDCP/RLC        protocols are proposed to handle PDCP duplication.    -   4. Procedures for reconfiguration of a duplication bearer to a        split bearer are proposed.    -   5. Procedures for reconfiguration of a duplication bearer to a        MCG/SCG bearer supporting a single radio link are proposed.    -   6. Support for UL PDCP link switching is introduced.

In a DC based scenario, the activation and/or deactivation of PDCPduplication can be achieved by the legacy bearer reconfigurationprocedures. For example, in deactivating duplication and using only asingle radio link, the network could perform a split bearer to MCGbearer reconfiguration. However, a bearer reconfiguration procedure is acomplex procedure involving a significant amount of signaling, e.g.including a data recovery procedure, at the expense of an increaseddelay as shown in the figure below. Therefore, this procedure might notbe suitable for activating/deactivating PDCP duplication in a dynamicmanner. To further demonstrate, consider FIG. 2 that illustrates abounce diagram with example interactions and messages that can be sentbetween entities.

Table 1 includes a list of abbreviations and/or definitions used in thefollowing discussion:

TABLE 1 Abbreviation Description/Definition Non-split a bearer whoseradio protocols are located in either the bearer MgNB or the SgNB to useMgNB or SgNB resource, respectively. Split bearer in dual connectivity,a bearer whose radio protocols are located in both the MgNB and the SgNBto use both MgNB and SgNB resources. BSR Buffer status report eNBEvolved Node-B gNB 5G Node-B GPRS General Packet Radio Service GSMGlobal System for Mobile Communications MN Master Node SN Secondary NodeDRB Data Radio Bearer carrying user plane data MCG Master Cell Group MMEMobility Management Entity L2 Layer 2 (data link layer) L3 Layer 3(network layer) MAC Medium Access Control NR New Radio PDCP Packet DataConvergence Protocol PDU Protocol Data Unit RB Radio Bearer RLC RadioLink Control RRC Radio Resource Control SCG Secondary Cell Group SIBSystem Information Block SR Scheduling Request SRB Signaling RadioBearer SDU Service Data Unit SN Sequence Number SRB Signalling RadioBearer carrying control plane data TCP Transmission Control Protocol UEUser Equipment UICC Universal Integrated Circuit Card UMTS UniversalMobile Telecommunication System UP User Plane

In the following the term eNB/gNB is used for the base station but it isreplaceable by any other radio access node, e.g. BS, eNB, gNB, AP, NRetc. Further the proposed method is applicable also to other types ofnetworks including IEEE 802.11 variants, GSM, GPRS, UMTS, LTE variants,CDMA2000, Bluetooth, ZigBee, Sigfoxx, etc. The described solution isalso applicable to the Next Generation Mobile Network (see 3GPP TS23.501 and 3GPP TS 23.502) where the nodes MME map to AMF and SMF andthe HSS maps to UDM/UDR and SGW/PGW map to the UPF.

Split Bearer with Duplication Mode

In one or more implementations, UE is configured by a network entity(NE) such as a base station (BS) or gNodeB (gNB) or the like with asplit bearer, i.e. a radio bearer in a dual connectivity scenario whoseradio protocols are split at either the master node (MN) or thesecondary node (SN) and belong to both MCG and SCG. NE or gNB canconfigure the split bearer to use either the split bearer operation asdefined for 5G (for throughput enhancement), to use only onelink/logical channel (by a specific configuration like settingul-DataSplitThreshold to a predefined value) or to use the PDCP packetduplication mode.

The radio bearer configuration of the split bearer, e.g. PDCPconfiguration, contains an information element (IE) indicating whetherpacket duplication is configured or not for the split bearer. In one ormore implementations, this information element is a Boolean variable. Incase the variable is set to false no packet duplication is supported forthis split bearer, i.e. legacy split bearer operation (for throughputenhancement) is supported. In case the Boolean variable is set to truepacket duplication is configured for the split bearer. In this example,duplication is an additional specific mode of the split bearer.

NE like gNB can dynamically activate/deactivate duplication for a splitbearer configured for duplication (Boolean set to True) by means of aMAC CE. According to one or more implementations, the default state fora split bearer configured for duplication is that duplication isdeactivated, i.e. duplication needs to be explicitly activated by a MACCE.

In response to deactivation of duplication, regular split beareroperation (as defined for 5G) is performed. UE follows the configuredparameters for the split bearer like ul-DataSplitThreshold andul-DataSplitDRB-ViaSCG Information Elements (IE) in order to determinethe data routing and buffer status reporting behaviour of the mobile,i.e. determine whether UE sends UL PDCP data via SCG or MCG of aconfigured split bearer or both. According to one or moreimplementations, ul-DataSplitThreshold is set to a new predefined valuefor a split bearer, e.g. infinity, in order to configure that only oneleg/radio link/logical channel/RLC entity is used for UL PDCP datatransmission. According to another alternative implementation,ul-DataSplitThreshold is not configured, hence all PDCP data issubmitted to one RLC entity as configured by an IE, e.g.ul-DataSplitDRB-ViaSCG.

In such a case the UE flushes according to another implementation theRLC transmission buffer of the “inactive” RLC entity, i.e., RLC entityof inactive/deactivated radio link. Flushing the PDCP PDUs/RLC PDUsstored in the transmission buffer ensures that those PDUs are notretransmitted, once the radio link is reactivated (in response toactivating duplication again), since this might even lead to TCPreducing the link rate or to HFN desynchronization. According to anotherimplementation the RLC entity of the “inactivated” radio link isre-established in response to deactivating duplication.

In another implementation UE initializes Bj for a previously “inactive”logical channel to zero in response to duplication being activatedagain. Alternatively, the Bj is initialized to zero for an “inactive”logical channel in response to duplication being deactivated. The MACentity maintains a variable Bj for each logical channel j. Bj shall beinitialized to zero in response to the related logical channel beingestablished, and incremented by the product PBR x TTI duration for eachTTI, where PBR is Prioritized Bit Rate of logical channel j. The UEdoesn't maintain the bucket status of a “inactive” logical channel inresponse to duplication being deactivated. In one or moreimplementations, UE cancels, if any, pending triggered SchedulingRequest/buffer status reporting procedures caused by data arrival of the“inactivated” logical channel in response to duplication beingdeactivated.

In one or more implementations, the RLC entity of the inactive radiolink/cell group respectively one leg of the split bearer is suspended inresponse to deactivating duplication. MAC entity does not report bufferstatus information for the suspended leg of the split bearer.Furthermore, the UE will flush the RLC buffer or alternativelyre-establish the “suspended” RLC entity.

In one or more implementations, the MAC/HARQ entity discards packetswhich are received for a RLC entity of an inactive leg of a split bearerin response to duplication having a deactivated state. RLC PDUs of an“inactive” RLC entity/logical channel might be still subject to HARQretransmission and therefore arrive after having disabled duplication.

According to one or more implementations, in response to duplicationbeing activated by MAC CE, ul-DataSplitThreshold is set to zero(implicitly by UE or explicitly signaled by gNB), which ensures thatboth links are used for UL PDCP data transmission and PDCP packet (PDU)duplication is applied. PDCP PDUs are generated upon request from lowerlayers, i.e. based on UL grant reception, and duplicated. In one or moreimplementations, the PDCP PDUs are delivered to both RLC entities.Details about the UE behaviour for PDCP packet duplication is disclosedin further implementations.

According to another implementation in response to duplication beingactivated by MAC CE, ul-DataSplitThreshold, ul-DataSplitDRB-ViaSCGInformation Elements (IEs) are ignored by the UE and packet duplicationis applied. PDCP PDUs are generated upon request from lower layers, i.e.based on UL grant reception, and duplicated. In one or moreimplementations, the PDCP PDUs are delivered to both RLC entities.Details about the UE behaviour for PDCP packet duplication is disclosedin further implementations.

According to another implementation in response to receiving areconfiguration message for a split bearer for which duplication isconfigured, e.g. RRC reconfiguration message, indicating thatduplication is de-configured, e.g. Boolean variable set to false, UEPDCP applies legacy split bearer operation, e.g. applyingul-DataSplitThreshold and ul-DataSplitDRB-ViaSCG IEs as configured. TheRLC, MAC protocol is continued without any interruption, e.g. RLCtransmissions are continued, HARQ operation is continued. UE comparesthe data available for transmission in PDCP layer against the configuredthreshold ul-DataSplitThreshold and performs the routing to lower layersand buffer status reporting accordingly as for the legacy split beareroperation. According to one or more implementations, each RLC entity/LCHof the split bearer may have, during duplication, a separate PDCP datavolume (the amount of PDCP data available for transmission may bedifferent for the two LCHs). In response to de-configuring theduplication for the split bearer, the UE PDCP uses the smaller of thetwo PDCP data volumes for comparison against the configured thresholdfor the purpose of routing and buffers status reporting.

According to a further implementation the PDCP receiver triggers andsends a PDCP status report indicating the successfully received PDCPSDUs to the PDCP transmitting entity. The PDCP transmitter may inresponse to receiving the PDCP status report update its transmissionbuffer in order to avoid (re)transmitting PDCP SDUs which were alreadysuccessfully received.

To further illustrate, consider Table 2 that illustrates the activationand deactivation of duplication relative to various settings asindicated below:

TABLE 2 Duplication activated Duplication deactivated Duplicationul-DataSplitThreshold = 0 split bearer operation. UE configured orfollows ul-DataSplitThreshold and ul-DataSplitThreshold andul-DataSplitDRB-ViaSCG ul-DataSplitDRB-ViaSCG are ignored orul-DataSplitThreshold = infinity (single link) or ul-DataSplitThresholdis not configured Duplication split bearer operation. UE followsul-DataSplitThreshold not and ul-DataSplitDRB-ViaSCG configuredSplit Bearer with New Configuration, Indicating the Duplication RLCEntity/Leg

In one or more implementations, UE is configured by a network entity(NE) such as a base station (BS), gNodeB (gNB) or the like with a splitbearer, i.e. a radio bearer in a dual connectivity scenario whose radioprotocols are split at either the master node (MN) or the secondary node(SN) and belong to both MCG and SCG. The radio bearer configuration,i.e. PDCP configuration, of the split bearer contains an informationelement (IE) indicating whether packet duplication is configured or not.In one or more implementations, this information element is a Booleanvariable.

In case the variable is set to false indicating that packet duplicationis not configured for this split bearer, i.e. split bearer operation issupported.

In case the Boolean variable is set to true indicating packetduplication is configured for the split bearer, the UE (PDCP layer)ignores the IEs ul-DataSplitThreshold, ul-DataSplitDRB-ViaSCG.

There is a new information element (IE), e.g. in PDCPconfiguration,configured for the split bearer configuring the RLC entity/link/LCH touse during a deactivated state of duplication, e.g. configuring which ofthe two RLC entities to use in response to a deactivated duplicationstate. This information element can be used in response to the splitbearer being configured for duplication.

NE like gNB can dynamically activate/deactivate duplication for a splitbearer configured for duplication (Boolean set to True) by means of aMAC CE. According to one or more implementations, the default state fora split bearer configured for duplication is that duplication isdeactivated, i.e. duplication needs to be explicitly activated by a MACCE.

According to one or more implementations, in response to duplicationbeing deactivated, the RLC entity configured via the new IE is used foruplink PDCP data transmission. PDCP will only submit PDCP PDUs to theconfigured RLC entity. In one or more implementations, UE continues toreport buffer status information for the “inactive” RLC entity/LCH. Theamount of data in PDCP for the purpose of buffer status reporting/PDCPdata volume is set to zero for the inactive LCH/RLC entity. In anotherimplementation UE doesn't report buffer status information for the“inactive” RLC entity/LCH.

According to one or more implementations, in response to duplicationbeing activated by MAC CE, ul-DataSplitThreshold andul-DataSplitDRB-ViaSCG IEs are ignored by the UE and packet duplicationis applied. PDCP PDUs are generated upon request from lower layers, i.e.based on UL grant reception, and duplicated. In one or moreimplementations, the PDCP PDUs are delivered to both RLC entities.Details about the UE behaviour for PDCP packet duplication is disclosedin further implementations.

According to another implementation in response to receiving areconfiguration message for a split bearer for which duplication isconfigured, e.g. RRC reconfiguration message, indicating thatduplication is de-configured, e.g. Boolean variable set to false, UEPDCP applies ul-DataSplitThreshold and ul-DataSplitDRB-ViaSCG IEs asconfigured. ul-DataSplitThreshold and ul-DataSplitDRB-ViaSCG areexamples used to demonstrate how the related functions for data routingand/or BSR purposes can be dynamically configured, and it is to beappreciated that alternate or additional IEs and/or information can beapplied and/or utilized without departing from the scope of the claimedsubject matter. The RLC, MAC protocol is continued without anyinterruption, e.g. RLC transmissions are continued, HARQ operation iscontinued. UE compares the data available for transmission in PDCP layeragainst the configured threshold ul-DataSplitThreshold and performs therouting to lower layers and buffer status reporting accordingly.According to one or more implementations, each RLC entity/LCH of thesplit bearer may have, in response to performing duplication, a separatePDCP data volume (the amount of PDCP data available for transmission maybe different for the two LCHs). In response to de-configuring theduplication for the split bearer, the UE PDCP uses the smaller of thetwo PDCP data volumes for comparison against the configured thresholdfor the purpose of routing and buffers status reporting.

According to a further implementation the PDCP receiver triggers andsends a PDCP status report indicating the successfully received PDCPSDUs to the PDCP transmitting entity. The PDCP transmitter may inresponse to receiving the PDCP status report update its transmissionbuffer in order to avoid (re)transmitting PDCP SDUs which were alreadysuccessfully received.

To further illustrate, consider Table 3 that illustrates the activationand deactivation of duplication relative to various settings asindicated below:

TABLE 3 Duplication activated Duplication deactivated Duplication Packetduplication is UE transmits UL PDCP configured applied. data only viaconfigured ul-DataSplitThreshold and LCH/RLC entityul-DataSplitDRB-ViaSCG ul-DataSplitThreshold and are ignoredul-DataSplitDRB-ViaSCG are ignored Duplication not split beareroperation. UE follows ul- configured DataSplitThreshold andul-DataSplitDRB-ViaSCGNew Bearer, i.e. Duplication Bearer, which can be used for CA and DC

According to one further implementation a new bearer type is introduced,i.e. duplication bearer, in order to support PDCP packet duplication. Aduplication bearer is characterized by having one PDCP entity and twoassociated RLC entities. In contrast to a split bearer, no PDCPparameters for split bearer operation like ul-DataSplitThreshold,ul-DataSplitDRB-ViaSCG IEs are configured for a duplication bearer.Furthermore, a duplication bearer could be used in a dual connectivityscenario, i.e. UE is configured with two cell groups, and also for thecase of carrier aggregation, i.e. UE is configured with multiple servingcells/component carriers controlled by one NE like gNB.

A duplication bearer is configured with a parameter indicating which RLCentity/logical channel/link/cell group is used in case duplication isdeactivated. The duplication bearer is generally applicable tosignalling data (SRB) as well as user plane data (DRB).

According to one or more implementations, duplication isactivated/deactivated by means of MAC control signalling for aduplication bearer. The default state for a duplication bearer is thatduplication is deactivated.

According to one or more implementations, in response to duplicationbeing deactivated by MAC CE, the configured RLC entity/LCH is used foruplink PDCP data transmission. PDCP will only submit PDCP PDUs to theconfigured RLC entity. According to one or more implementations, UEcontinues operation of the other “inactive” RLC entity, i.e. RLC(re)transmissions are continued after duplication has been deactivateduntil buffers are empty. The data available for transmission inPDCP/PDCP data volume for the “deactivated” logical channel/RLC entityis set to zero, i.e. UE only reports RLC data volume/buffer information.

According to another implementation in response to receiving anindication from NE directing the UE to deactivate duplication, the UEflushes the RLC transmission buffer of the deactivated RLC entity, i.e.RLC entity/logical channel which is not used for data transmission asindicated by configuration. The data available for transmission in PDCPfor the “deactivated” logical channel/RLC entity is set to zero oralternatively MAC does not report buffer status information for thedeactivated RLC entity/logical channel at all. According to anotherimplementation the UE re-establishes the RLC entity which is not usedfor data transmission.

According to another implementation, the UE suspends the logicalchannel/RLC entity which is not used for data transmission in responseto the NE directing the UE to deactivate duplication. MAC entity doesnot report buffer status information for the suspended logical channel.UE further re-establish the RLC entity of the suspended logical channelor alternatively flushes the RLC buffer.

In another implementation UE initializes Bj for the previously“inactive”/suspended logical channel to zero in response to duplicationbeing activated. Alternatively, the Bj is initialized to zero for an“inactive” logical channel in response to duplication being deactivated.The MAC entity maintains a variable Bj for each logical channel j. Bjshall be initialized to zero in response to the related logical channelbeing established, and incremented by the product PBR×TTI duration foreach TTI, where PBR is Prioritized Bit Rate of logical channel j. The UEdoesn't maintain the bucket status of a “inactive”/suspended logicalchannel in response to duplication being deactivated. In one or moreimplementations, UE cancels, if any, triggered Scheduling Requestprocedures/buffer status reporting procedures caused by data arrival ofthe “inactivated”/suspended logical channel in response to duplicationbeing deactivated.

In one or more implementations, the MAC entity discards packets whichare received for a RLC entity which is suspended or “inactive” inresponse to duplication being deactivated. RLC PDUs of an “inactive” RLCentity/logical channel might be still subject to HARQ retransmission andtherefore arrive after having disabled duplication.

According to one or more implementations, in response to duplicationbeing activated by MAC CE, Packet duplication is applied. PDCP PDUs aregenerated upon request from lower layers, i.e. based on UL grantreception, and duplicated. In one or more implementations, the PDCP PDUsare delivered to both RLC entities. Details about the UE behaviour forPDCP packet duplication is disclosed in further implementations.

To further illustrate, consider Table 4 that illustrates the activationand deactivation of duplication relative to the duplication bearer:

TABLE 4 Duplication activated Duplication deactivated Duplication bearerPacket duplication is UE transmits UL PDCP configured applied. data onlyvia configured LCH/RLC entity

Detailed UE Behavior for PDCP Packet Duplication

According to one or more implementations, in response to duplicationbeing activated by MAC CE, packet duplication is applied. PDCP PDUs aregenerated upon request from lower layers, i.e. based on UL grantreception, and duplicated. In one or more implementations, the PDCP PDUsare delivered to both RLC entities. Details about the UE behaviour forPDCP packet duplication is disclosed in further implementations).

In response to duplication being configured and activated, PDCP layergenerates PDCP PDUs upon request from an associated RLC entity, e.g. inresponse to the UL grant being received. In one or more implementations,the PDCP layer duplicates the generated PDCP PDUs and submits the PDUsimmediately to both RLC entities, even though only one of the twoassociated RLC entities might have requested new PDCP data. Pushing downthe PDCP PDUs immediately to both RLCs may lead to that some data beingstuck in an RLC for which no grant will arrive (for some time). However,on the other hand, the advantage would be that PDCP layer doesn't needto keep track which PDCP PDUs have been already submitted to a RLCentity. PDCP operation would be same as for a non-duplication bearer.Also, the PDCP buffer status, i.e. data volume in PDCP for the purposeof buffer status reporting is the same for both RLC entities.

In order to avoid that PDCP PDUs for which successful delivery has beenalready confirmed for one link/logical channel are subject to aduplicate-transmission over the other link/logical channel, the UE shallaccording to one or more implementations, discard those packets.According to one or more implementations UE removes PDCP PDUs fromtransmission buffer of one radio link respectively RLC entity which werealready successfully transmitted via the other logical channel/RLCentity based on received RLC status reports. RLC layer will inform PDCPlayer about the successfully transmitted PDCP SDUs. PDCP layer will sendthe PDCP discard notification to the other RLC entity. Hence a newadditional trigger for the PDCP discard notification is introduced. Inaddition to the expiry of the discard timer, the UE PDCP shall triggerdiscard notification to a RLC entity for a duplication bearer uponconfirmation of successful transmission of PDCP PDUs/SDUs over the otherRLC entity/logical channel.

In another implementation the removal/discarding of packets is based onreceived PDCP status reports. For DL the UE would need to send PDCPstatus reports to the NE, which could use this information fordiscarding packets which have been already successfully received by theUE from the buffer. For UL the UE PDCP layer indicates in response tohaving received a PDCP status report the RLC entity to discard packetswhich have been already successfully transmitted—via the other RLCentity/logical channel. In one or more implementations, the UE let thePDCP discard timer expire for those PDCP SDUs which are indicated in thePDCP status report as successfully transmitted respectively received.Hence a new additional trigger for the PDCP discard notification isintroduced. The UE PDCP shall trigger discard notification to a RLCentity for a bearer operating in duplication mode upon confirmation ofsuccessful transmission of PDCP PDUs/SDUs over the other RLCentity/logical channel.

In another implementation in response to duplication being configuredand activated, PDCP layer only submits generated PDCP PDUs to lowerlayers upon request. PDCP PDUs are generated and stored in the PDCPlayer, i.e. PDCP (re)transmission buffer. In case only one of the RLCentities requests new PDCP PDUs (based on a received grant) fortransmission the generated PDCP PDUs are only submitted to therequesting RLC entity. Upon request from the second RLC entity the PDCPPDUs are submitted to the second RLC entity. According to thisimplementation the PDCP layer maintains two state variables one for eachof the two associated RLC entities. Each state variable points to thelast submitted PDCP SDU/PDU (submitted to the corresponding RLC entity).In maintaining two state variables/pointers, the PDCP layer is aware ofwhich PDCP SDU/PDU needs to be submitted to the corresponding RLC entityupon request. Since the request rate and size is different for the twoRLC entities, e.g. UL grants arrives at different point of times and maybe of different size, there need to be two independent state variables.According to one or more implementations, PDCP PDUs are stored in thePDCP layer until the corresponding PDCP PDU has been submitted to bothRLC entities. According to another implementation the PDCP PDU stored inPDCP layer can be discarded upon successful delivery confirmation, i.e.successful PDCP PDU transmission over one link, the PDCP PDUs shall notbe transmitted again via the other link. Each of the two LCHs has adifferent PDCP data volume (i.e. amount of PDCP data for the purpose ofbuffer status reporting) according to one or more implementations, sinceeach LCH has a different PDCP status as further described herein.

Reconfiguration from Duplication Bearer to Regular Split Bearer

According to one or more implementations, in response to receiving amessage indicating the reconfiguration from a duplication bearer to asplit bearer, UE reconfigures the PDCP entity in accordance with theindicated configuration of the split bearer, i.e. PDCP-Config(ul-DataSplitThreshold, ul-DataSplitDRB-ViaSCG). Similarly, the UEreconfigures the RLC entities and/or the corresponding logical channelsin accordance with the RLC-Config and logicalChannelConfig. The RLC, MACprotocol is continued without any interruption, e.g. RLC transmissionsare continued, HARQ operation is continued. UE PDCP compares the dataavailable for transmission in PDCP layer against the configuredthreshold ul-DataSplitThreshold and performs the routing to lower layersand buffer status reporting accordingly. According to one or moreimplementations, each RLC entity/LCH of the split bearer may have, inresponse to performing duplication, a separate PDCP data volumecalculation (the amount of PDCP data available for transmission may bedifferent for the two LCHs). In response to reconfiguring the bearertype from a duplication bearer to a split bearer, the UE PDCP uses thesmaller of the two PDCP data volumes for comparison against theconfigured threshold for the purpose of routing and buffers statusreporting.

According to one or more implementations the UE triggers a PDCP statusreport (indicating which PDCP SDUs have been successfully received) inresponse to receiving a receiving a bearer reconfiguration message(duplication bearer to split bearer). In another implementation the UEreceives a PDCP status report, e.g. together with the bearerreconfiguration message, and acts upon the received PDCP status report,i.e. PDCP PDUs/SDUs confirmed to be successfully received are removedfrom the corresponding PDCP/RLC (transmission) buffer.

Reconfiguration from Duplication Bearer to Non-Split Bearer

According to one or more implementations, bearer type reconfigurationfrom a duplication bearer to a non-split bearer, i.e. one PDCP entityassociated with only one RLC entity is supported. In response toreceiving a message indicating the reconfiguration of duplication to aMCG or SCG bearer, the UE according to one or more implementations,releases one RLC entity of the two RLC entities and the correspondinglogical channel as indicated in the reconfiguration message. The MAClayer operation continues, i.e. no reset of MAC layer. Packets of theremoved LCH are discarded upon receipt, i.e. packets from the removedLCH might be still subject to HARQ (re)transmissions. Before removingthe RLC entity, RLC informs PDCP layer about the PDCP PDUs/SDUs forwhich successful reception was confirmed. Alternatively, a PDCP statusreport is triggered and transmitted in response to the bearer typereconfiguration. BSR/Scheduling request(s) triggered due to data arrivalin the LCH which is to be removed are cancelled when pending upon thereconfiguration. Alternatively, the B SR/SR procedures are not affectedby the removal of a LCH/RLC entity and continue.

Indication of RLC Reaching the Maximum Number of Retransmissions to gNB

According to one or more implementations, the UE informs the gNB thatthe maximum number of RLC retransmissions is reached for a logicalchannel of a bearer which is operated in duplication mode. For the casethat PDCP duplication is used in a carrier aggregation scenario, i.e. UEis configured with multiple component carriers/serving cells, thelogical channel prioritization procedure ensures that duplicate PDCPPDUs are sent on different carriers. In one or more implementations, theNE like gNB configures which carrier/serving cell the logical channelsof a bearer applying PDCP duplication, e.g. a duplication bearer or asplit bearer operating in duplication mode, are allowed to usetransmission. Since the duplicates are sent on a different carrieralways, the failure of that carrier, i.e. upon reaching the maximumnumber of RLC retransmission, should lead to a deactivation or removalof that carrier/serving cell or reconfiguration of the cell group, butnot to a Radio link failure (RLF) like in LTE.

According to one or more implementations, the UE triggers a serving cellfailure information procedure in response to a logical channel of abearer applying PDCP duplication reaches the maximum number of RLCretransmissions. The purpose of this procedure is to inform the NE/gNBabout a serving cell failure the UE has experienced, so that network/gNBcan deactivate or remove for example the serving cell/carrier where thefailure was experienced. According to one or more implementations, theUE stops all uplink transmissions on the cell/carrier where a failureoccurred, i.e. maximum number of RLC retransmissions was reached.

UL PDCP Link Switching

For NR, some mode of operating an UL split bearer operation may be touse only one Cell group/link at a time for uplink data transmission andswitch the link depending on e.g., channel status, traffic load etc. ULlink switching may be beneficial to support fast recovery for most eMBBapplications. In NR Dual connectivity and in EN-DC architecture, the ULsplit bearer may be used in most cases for fast recovery, e.g. the LTEleg is used as a backup leg and the NR leg is used for mosttransmissions, e.g. the NR SCG may have a large bandwidth. In this case,the NR SCG throughput is sufficient to support eMBB servicerequirements. LTE MCG may be useful as a backup link for data recoveryin response to the NR SCG experiencing a blockage, i.e. in a millimeterwave band.

UL link switching could be configured and operated for a split bearer aswell as for a duplication bearer. In the case that the split bearerarchitecture is used to support UL switching, the split bearer isconfigured with an additional switching mode, i.e. IE indicating that ULlink switching is configured. According to one or more implementations,a split bearer could be operated in three different modes, i.e. splitmode, duplication mode and switching mode. In case a duplication bearer(as disclosed in above implementations) UL switching could be supportedby changing the configured link which is used for the case in responseto duplication being deactivated, i.e. switching the configured UL byRRC reconfiguration. Alternatively, a new parameter/IE could beintroduced for a duplication bearer, which indicates that the bearer isconfigured for the switching mode.

According to one or more implementations, in response to receivingcontrol signaling indicating the switch of the UL link/direction fromone RLC entity to the other RLC entity, the UE sets the data volume/dataavailable for transmission in the PDCP layer to zero for the link whichis not used for UL PDCP data transmission. UE only reports RLC datavolume/buffer occupancy for this LCH/link in the buffer status report.

According to one or more further implementation, in response toreceiving control signaling indicating the switch of the ULlink/direction from one RLC entity to the other RLC entity, the UE(re)transmits RLC PDUs pending for initial transmission (preprocessedPDCP PDUs) in the RLC entity which was used for UL PDCP datatransmission before the link switch via the other RLC entity. Accordingto one or more implementations, upon a UL link switch only RLCretransmissions and RLC status reports are send via the “inactive” RLCentity/LCH, i.e. the RLC/LCH which is not used for PDCP UL datatransmissions.

Upon reception of the control signaling indicating a link switch, the UEroutes according to one or more implementations, all PDCP PDUs to theRLC entity/logical channel of the indicated link. According to one ormore implementations, the RLC entity of the leg/link which was usedbefore the signaled link switch indicates to the PDCP entity the RLCSDUs which were not yet acknowledged, e.g., by RLC status report. The UEretransmits the not yet acknowledged RLC SDUs via the new link used foruplink data transmission, i.e. link indicated in the PDCP control PDU orMAC CE.

According to one or more implementations, the UE flushes the RLCtransmission buffer and resets the RLC transmission state variables. Inone or more implementations, the RLC entity of the deactivated link,e.g., link which was previously used for uplink data transmission, isreestablished.

According to one or more implementations, the network entity sends aPDCP status report for the split bearer together with the indication toconfigure/switch the link for uplink PDCP PDU transmission. According toa further implementation, the UE upon reception of the PDCP statusreport retransmits the PDCP SDUs not yet acknowledged by the networkentity via the link/leg indicated to be used for uplink datatransmission. In one or more implementations, the UE flushes the RLCtransmission buffer and resets the RLC transmission state variables ofthe leg which is not used for uplink data transmission. In one or moreimplementations, the RLC entity of the deactivated link isreestablished.

Now consider FIG. 3 that illustrates an example method 300 that operatesin a plurality of operating modes associated with packet duplication inaccordance with one or more implementations. Generally, any services,components, modules, methods, and/or operations described herein can beimplemented using software, firmware, hardware (e.g., fixed logiccircuitry), manual processing, or any combination thereof. For instance,method 300 can be performed by UE protocol module 108 and/or UEduplication control module 110 of FIG. 1. Some operations of the examplemethod may be described in the general context of executableinstructions stored on computer-readable storage memory that is localand/or remote to a computer processing system, and implementations caninclude software applications, programs, functions, and the like.Alternately or in addition, any of the functionality described hereincan be performed, at least in part, by any combination of hardware,software and/or firmware. While method 300 illustrates steps in aparticular order, it is to be appreciated that any specific order orhierarchy of the steps described here is used to illustrate an exampleof a sample approach. Other approaches may be used that rearrange theordering of these steps. Thus, the order steps described here may berearranged, and the illustrated ordering of these steps is not intendedto be limiting.

At block 302, user equipment establishes a radio bearer that can be usedto communicate with a first serving cell and a second serving cell viathe various network components (network component 106-1, networkcomponent 106-2, and/or network component 106-n of FIG. 1). In variousimplementations, the radio bearer can include a PDCP protocol entity, afirst radio link control (RLC) protocol entity for the first servingcell, and a second RLC protocol entity for the second serving cell.

At block 304, the user equipment configures a threshold value and arouting value, e.g. a parameter indicating one of the multiple radiolink control (RLC) protocol entities, of the radio bearer.

At block 306, the user equipment duplicates at least one Protocol DataUnit (PDU) associated with the PDCP protocol entity, and sends the atleast one PDCP PDU and the duplicate PDCP PDU to the first RLC protocolentity, and to the second RLC protocol entity.

At block 308, the user equipment receives a signaling message from anetwork entity indicating to stop duplicating, such as the duplicatingoccurring at block 306.

At block 310, and responsive to receiving the indication, the userequipment submits at least one PDU associated with the PDCP protocolentity to either the first RLC protocol entity or the second RLCprotocol entity, based on the configured threshold value and the routingvalue. In various implementations, the at least one PDU is sent to oneof the RLC protocol entities without duplication.

As another example, consider now FIG. 4 that illustrates an examplemethod 400 that uses different packet duplication operating modes inaccordance with one or more implementations. Generally, any services,components, modules, methods, and/or operations described herein can beimplemented using software, firmware, hardware (e.g., fixed logiccircuitry), manual processing, or any combination thereof. For instance,method 400 can be performed by UE protocol module 108 and/or UEduplication control module 110 of FIG. 1. Alternately or additionally,portions of method 400 can be performed by NE protocol module 114 and/orNE protocol module 116 of FIG. 1. Some operations of the example methodmay be described in the general context of executable instructionsstored on computer-readable storage memory that is local and/or remoteto a computer processing system, and implementations can includesoftware applications, programs, functions, and the like. Alternately orin addition, any of the functionality described herein can be performed,at least in part, by any combination of hardware, software and/orfirmware. While method 400 illustrates steps in a particular order, itis to be appreciated that any specific order or hierarchy of the stepsdescribed here is used to illustrate an example of a sample approach.Other approaches may be used that rearrange the ordering of these steps.Thus, the order steps described here may be rearranged, and theillustrated ordering of these steps is not intended to be limiting.

At step 402, various implementations establish a radio bearer forcommunications over a communications network. For example, userequipment can establish the radio bearer to operate in various modes,such as a mode that enables the radio bearer to communicate withmultiple serving cells, multiple network entities, and so forth.Alternately or additionally, the radio bearer can operate using carrieraggregation modes of communication. Some network entities establishand/or manage the radio bearer associated with communications betweenthe user equipment and the network entity. Various implementations ofthe radio bearer include a PDCP protocol entity, and multiple RLCprotocol entities, examples of which are provided herein. In someimplementations, the PDCP protocol entity and/or the multiple RLCprotocol entities are managed by a protocol stack with multiple layers.In carrier aggregation mode, some implementations associate a first RLCprotocol entity with a first carrier of multiple carriers and associatea second RLC protocol entity with a second carrier of the multiplecarriers.

At step 404, one or more implementations determine whether packetduplication for the radio bearer is enabled. As one example, userequipment can receive various IEs over the communication network, suchas ul-DataSplitThreshold, ul-DataSplitDRB-ViaSCG, and/or a Booleanvariable, and analyse the IEs to determine state information for packetduplication (e.g., enabled or disabled). This can include extractingand/or analysing the IEs at various levels of the protocol stack, suchas the MAC layer and/or a PDCP layer as further described herein.Alternately or additionally, various implementations process MAC controlsignals to obtain packet duplication state information. It is to beappreciated that ul-DataSplitThreshold, ul-DataSplitDRB-ViaSCG, and theBoolean variable are used here for discussion purposes, and thatalternate or additional IEs can extracted, analysed, and/or utilizedwithout departing from the scope of the claimed subject matter. Someimplementations support a network entity setting various IEs to enableand/or disable packet duplication to indicate which packet duplicationoperating mode is the current operating mode, and transmitting the IEsto the user equipment to inform the user equipment of the currentoperating mode.

In response to determining that packet duplication is enabled, variousimplantations use in a first operating mode associated with packetduplication at 406. For example, user equipment duplicates uplink PDCPdata associated with the PDCP protocol entity over the communicationsnetwork by submitting a first instance of the uplink PDCP data to afirst RLC protocol entity for transmission, and submitting a secondinstance of the uplink PDCP data to the second RLC entity fortransmission. The user equipment continues to use and/or operate in thefirst operating mode, and the method returns to 404 to evaluate newinformation as it is received to determine whether to continue using thefirst mode of operation or whether to use a different mode of operationthat is associated with packet duplication. In response to determiningthat packet duplication is disabled at 404, the method proceeds to 408.

At 408, one or more implementations determine whether a threshold valueis set to a predefined value. For instance, various implementationsextract ul-DataSplitThreshold using the MAC layer of the UE protocolmodule, and determine whether the threshold value equates to apredefined value that corresponds to infinity. While described in thecontext of evaluating ul-DataSplitThreshold, it is to be appreciatedthat other IEs can be extracted and/or evaluated as well to determinewhether the threshold is set to the predefined value. In response todetermining the threshold is set to the predefined value, the methodproceeds to 410.

Various implementations use a second mode of operation associated withpacket duplication at 410. The second mode of operation can includeoperating in a split bearer mode of operation that uses one of the firstRLC protocol entity and the second RLC protocol entity for transmittingthe uplink PDCP data over the communications network, and deactivatestransmission of the uplink PDCP data over a radio link associated withthe other one of the first RLC protocol entity and the second RLCprotocol entity which is not used for the uplink PDCP data. As oneexample, various implementations receive an RRC message that includes anIE associated with transmitting the uplink PDCP data via the splitbearer, extracts the IE from the RRC, and uses the IE to configure whichRLC protocol entity of the first RLC protocol entity and the second RLCprotocol entity to use for transmitting the uplink PDCP data.Alternately or additionally, the second mode of operation flushes atransmission buffer and/or resets transmission state variables for theRLC protocol entity which is not used for the uplink PDCP data. Inresponse to determining that packet duplication has switched fromdisabled to enabled, various implementations of the second operatingmode reactivate the radio link associated with the RLC protocol entitynot used for transmitting the uplink PDCP data. Accordingly, the secondoperating mode can change which RLC protocol entity is used in the splitbearer mode. For instance, user equipment can receive control signalingthat indicates to switch from the original RLC protocol entity used fortransmitting the uplink PDCP data to the other RLC protocol entity notused. In response to the control signal, the user equipment can use theother RLC protocol entity as the newly designated RLC protocol entityfor transmitting the uplink PDCP data. In turn and in response to usingthe newly designated RLD protocol entity, one or more implementationsretransmit not yet acknowledged data packets initially designated fortransmission on the original RLC protocol entity on the newly designatedRLC protocol entity. The not yet acknowledged data packets can beidentified in any suitable manner, such as through an RLC status reportassociated with the original RLC protocol entity. The variousimplementations continue to use and/or operate in the second operatingmode, and the method returns to 404 to evaluate new information as it isreceived to determine whether to continue using in the second mode ofoperation or whether to operate in a different mode of operation.

Returning to 408, the method proceeds to 412 in response to determiningthat the threshold value is set to another value than the predefinedvalue. At 412, one or more implementations operate in a third operatingmode associated with packet duplication, where the third operating modefunctions a split bearer operating mode. The third operating mode caninclude accessing radio bearer configuration parameters to determine howto send the uplink PDCP data over the communications network. Forexample, the uplink PDCP data can be transmitted over the communicationsnetwork using only the first RLC protocol entity, using only the secondRLC protocol entity, or using both of the first RLC protocol entity andthe second RLC protocol entity. The various implementations continue tooperate in the third operating mode, and the method returns to 404 toevaluate new information as it is received to determine whether tocontinue using in the third mode of operation or whether to operate in adifferent mode of operation.

Accordingly, the user equipment and/or network entity can supportchanging between packet duplication operating modes by communicatinginformation via the communication network, such as first using anoperating mode with packet duplication disabled (e.g., in a legacysplit-bearer mode) and then using a second operating mode with packetduplication being enabled (e.g. a switching mode of operation thatutilizes one link, a packet duplication mode of operation that transmitsduplicate data on multiple links, etc.). In response to functioning inan operating mode associated with transmitting duplicate data over anetwork, various implementations submit a respective instance of thedata to each respective RLC protocol entity identified for duplicatedata transmission, such as multiple instances of uplink PDCP data,effective to transmit duplicates the same data as further describedherein.

Having considered a discussion of using different operating modesassociated with packet duplication that can be dynamically changed inaccordance with one or more implementations, consider now examplecomputing devices that can implement the various implementationsdescribed above.

Example Devices

FIG. 5 illustrates various components of an example user equipmentdevice 400 in which selective packet duplication can be implemented,while FIG. 6 illustrates various components of an example network entitydevice 600 in which user selective packet duplication can beimplemented. In some implementations, user equipment device 500 andnetwork entity device 600 have at least some similar components.Accordingly, for the purposes of brevity, FIG. 5 and FIG. 6 will bedescribed together. Similar components associated with FIG. 5 will beidentified as components having a naming convention of “5XX”, whilecomponents associated with FIG. 6 will be identified as componentshaving a naming convention of “6XX”. Conversely, components distinct toeach device will be described separately. User equipment device 500 andnetwork entity device 600 can be, or include, many different types ofdevices capable of implementing dynamic connectivity configuration of awireless networking device and/or user device-initiated connectivityconfiguration in accordance with one or more implementations.

User equipment device 500/network entity device 600 includescommunication transceivers 502/communication transceivers 602 thatenable wired or wireless communication of device data 504/device data604, such as received data and transmitted data. While referred to as atransceiver, it is to be appreciated that communication transceivers502/communication transceivers 602 can additionally include multipleantennas that can be configured differently from one another, or work inconcert to generate beam-formed signals. For example, a first antennacan transmit/receive omnidirectional signals, and subsequent antennastransmit/receive beam-formed signals. Example communication transceiversinclude Wireless Personal Area Network (WPAN) radios compliant withvarious Institute of Electrical and Electronics Engineers (IEEE) 802.15(Bluetooth™) standards, Wireless Local Area Network (WLAN) radioscompliant with any of the various IEEE 802.11 (WiFi™) standards,Wireless Wide Area Network (WWAN) radios for cellular telephony(3GPP-compliant, 4G-compliant, 5G-compliant), wireless metropolitan areanetwork radios compliant with various IEEE 802.16 (WiMAX™) standards,and wired Local Area Network (LAN) Ethernet transceivers.

User equipment device 500/network entity device 600 may also include oneor more data input ports 506/data input ports 606 via which any type ofdata, media content, and/or inputs can be received, such asuser-selectable inputs to the device, messages, music, televisioncontent, recorded content, and any other type of audio, video, and/orimage data received from any content and/or data source. The data inputports may include Universal Serial Bus (USB ports), coaxial cable ports,and other serial or parallel connectors (including internal connectors)for flash memory, Digital Versatile Discs (DVDs), Compact Discs (CDs),and the like. These data input ports may be used to couple the device toany type of components, peripherals, or accessories such as microphones,cameras, and/or modular attachments.

User equipment device 500/network entity device 600 includes aprocessing system 508/processing system 608 of one or more processors(e.g., any of microprocessors, controllers, and the like) and/or aprocessor and memory system implemented as a system-on-chip (SoC) thatprocesses computer-executable instructions. The processor system may beimplemented at least partially in hardware, which can include componentsof an integrated circuit or on-chip system, an application-specificintegrated circuit (ASIC), a field-programmable gate array (FPGA), acomplex programmable logic device (CPLD), and other implementations insilicon and/or other hardware. Alternatively, or in addition, the devicecan be implemented with any one or combination of software, hardware,firmware, or fixed logic circuitry that is implemented in connectionwith processing and control circuits, which are generally identified asprocessing and control 510/processing and control 610. User equipmentdevice 500/network entity device 600 may further include any type of asystem bus or other data and command transfer system that couples thevarious components within the device. A system bus can include any oneor combination of different bus structures and architectures, as well ascontrol and data lines.

User equipment device 500/network entity device 600 also includescomputer-readable storage memory or memory devices 512/memory devices612 that enable data storage, such as data storage devices that can beaccessed by a computing device, and that provide persistent storage ofdata and executable instructions (e.g., software applications, programs,functions, and the like). Examples of the computer-readable storagememory or memory devices 512/memory devices 612 include volatile memoryand non-volatile memory, fixed and removable media devices, and anysuitable memory device or electronic data storage that maintains datafor computing device access. The computer-readable storage memory caninclude various implementations of random access memory (RAM), read-onlymemory (ROM), flash memory, and other types of storage media in variousmemory device configurations. User equipment device 500/network entitydevice 600 may also include a mass storage media device.

The computer-readable storage memory provides data storage mechanisms tostore the device data 504/device data 604, other types of informationand/or data, and various device applications 514/device applications 614(e.g., software applications). For example, an operating system516/operating system 616 can be maintained as software instructions witha memory device and executed by the processor system 508/processorsystem 608. The device applications may also include a device manager,such as any form of a control application, software application,signal-processing and control module, code that is native to aparticular device, a hardware abstraction layer for a particular device,and so on. User equipment device 500 includes protocol stack module 518and duplication control module 520, while network entity device 600includes protocol stack module 618 and duplication control module 620.

Protocol stack module 518/protocol stack module 618 representfunctionality that implements any suitable protocol used to communicatebetween devices. This can include any suitable combination ofinformation, signals, data packets, message ordering, transmissionfrequencies, modulation types, and/or handshaking used betweencommunication devices to interpret transmitted data and/or to conveyinformation. Some implantations of protocol stack module 518/protocolstack module 618 implement a protocol stack that follows the OSI modelas further described herein. Here, protocol stack module 518 includesduplication control module 420, while protocol stack module 618 includesduplication control module 520. While illustrated here as residingwithin protocol stack module 518/protocol stack module 618, otherimplementations of duplication control module 520/duplication controlmodule 620 reside outside its respective protocol stack module such thatthe duplication control module controls various aspects of packetduplication within the corresponding protocol stack. Here, duplicationcontrol module 520/duplication control module 620 representfunctionality that dynamically and/or selectively enables and disablespacket duplication as further described herein

User equipment device 500 also includes an audio and/or video processingsystem 522 that generates audio data for an audio system 524 and/orgenerates display data for a display system 526.

The audio system 524 and/or the display system 526 may include anydevices that process, display, and/or otherwise render audio, video,display, and/or image data. Display data and audio signals can becommunicated to an audio component and/or to a display component via anRF link, S-video link, HDMI (high-definition multimedia interface),composite video link, component video link, DVI (digital videointerface), analog audio connection, or other similar communicationlink, such as media data port 528. In implementations, the audio systemand/or the display system are integrated components of the exampledevice. Alternatively, the audio system and/or the display system areexternal, peripheral components to the example device.

Conclusion

Various discussions here describe selectively enabling and disablingpacket duplication in a wireless network, such as a wireless networkthat employs Packet Data Convergence Protocol (PDCP). In some aspects,user equipment can dynamically control packet duplication, while inother aspects, a network entity directs the user equipment dynamicallyenable or disable packet duplication.

One or more implementations provide a computing device comprising: aprocessor system that implements a protocol module to: establish a radiobearer to communicate with at least one network entity over acommunications network, the radio bearer comprising a Packet DataConvergence Protocol (PDCP) protocol entity, a first Radio Link Control(RLC) protocol entity associated with a first radio link over thecommunications network, and a second RLC protocol entity associated witha second radio link over the communications network; receive, over thecommunications network, PDCP configuration information that includes aBoolean variable associated with PDCP packet duplication; determine astate of PDCP packet duplication based, at least in part, on the Booleanvariable; responsive to determining that the state indicates that PDCPpacket duplication is enabled, use a first mode of operation of aplurality of modes of operations associated with PDCP packet duplicationusing the PDCP protocol entity; and responsive to determining that thestate indicates that PDCP packet duplication is enabled, use a secondmode of operation of the plurality of modes or a third mode of operationof the plurality of modes by: receiving information over thecommunications network that includes a threshold value; extracting,using a Medium Access Control (MAC) layer associated with the protocolmodule, the threshold value from the information; using the second modeof operation in response the MAC layer determining that the thresholdvalue is set to a predefined value associated with the second mode ofoperation; and using the third mode of operation in response to the MAClayer determining that the threshold value is set to a value other thanthe predefined value, wherein to use the first mode of operation, theprocessor system implements the protocol module to: duplicate the uplinkPDCP data over the communications network by transmitting a firstinstance of the uplink PDCP data using the first RLC protocol entity,and transmitting a second instance of the PDCP data using the second RLCprotocol entity effective to duplicate the uplink PDCP data, wherein touse the second mode of operation, the processor system implements theprotocol module to: use one of the first RLC protocol entity and thesecond RLC protocol entity for the uplink PDCP data transmissions overthe communications network; and deactivate the uplink PDCP datatransmissions using the other one of the first RLC protocol entity andthe second RLC protocol entity that is not used for the uplink PDCP datatransmissions, and wherein to use the third mode of operation, theprocessor system implements the protocol module to: access radio bearerconfiguration parameters to determine whether to send the uplink PDCPdata: using only the first RLC protocol entity; using only the RLCprotocol entity; or using both of the first RLC protocol entity and thesecond RLC protocol entity.

In one or more implementations, to use the second mode of operation, theprocessor system implements the protocol module to: receive, via thecommunications network, a Radio Resource Control (RRC) message thatincludes an Information Element (IE) associated with transmitting theuplink PDCP data via a split bearer; process the RRC message to extractthe IE; and use the IE to configure which RLC protocol entity of thefirst RLC protocol entity and the second RLC protocol entity to use forsaid transmitting, over the communications network, the uplink PDCP datavia the split bearer.

In one or more implementations, the communications network comprises aLong-Term Evolution (LTE) based network.

In one or more implementations, the computing device comprises acellular mobile phone.

Although various aspects of dynamically selecting packet duplicationhave been described in language specific to features and/or methods, thesubject of the appended claims is not necessarily limited to thespecific features or methods described. Rather, the specific featuresand methods are disclosed as example implementations, and otherequivalent features and methods are intended to be within the scope ofthe appended claims. Further, various different implementations aredescribed and it is to be appreciated that each described implementationcan be implemented independently or in connection with one or more otherdescribed implementations.

Embodiments may be practiced in other specific forms. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

What is claimed is:
 1. A method of a user equipment comprising:establishing a radio bearer to communicate with at least one networkentity, the radio bearer comprising a Packet Data Convergence Protocol(“PDCP”) protocol entity associated with a first Radio Link Control(“RLC”) protocol entity and with a second RLC protocol entity;determining whether PDCP packet duplication associated with the PDCPprotocol entity is to be activated; communicating with a mobilecommunication network according to a packet duplication mode ofoperation in response to determining that PDCP packet duplication is tobe activated; determining whether a split threshold value of the PDCPprotocol entity is set to a predefined value in response to determiningthat PDCP packet duplication is not to be activated; communicating withthe mobile communication network according to a first split bearer modeof operation in response to determining that the split threshold valueis set to the predefined value; and communicating with the mobilecommunication network according to a second split bearer mode ofoperation in response to determining that the split threshold value isnot set to the predefined value, wherein the first split bearer mode ofoperation comprises: selecting one of the first RLC protocol entity andthe second RLC protocol entity to be a primary RLC protocol entity; andtransmitting uplink PDCP data exclusively over a data path associatedwith the primary RLC protocol entity, wherein the second split bearermode of operation comprises: selecting one of the first RLC protocolentity and the second RLC protocol entity to be a primary RLC protocolentity; and selectively sending uplink PDCP data to the primary RLCprotocol entity or to a non-primary RLC protocol entity based on anamount of uplink PDCP data as compared to the split threshold value.